Whenever someone has to do this on an electric car that turns itself off after half an hour (or 90 seconds, looking at you Audi Q8 eTron), just jam something lightly onto the brake pedal, so far that has kept them all on. Cardboard boxes of filament work well for me.

I’d hate for the update to fail because the puny 12V boat anchor runs out of juice with all the kWh sitting unused under the floor.